The direction of movement (up or down) can be permanently the same, or be controlled by personnel according to the time of day, or automatically be controlled by whoever arrives first, someone at the bottom or at the top (of course the system is programmed such that the direction is not reversed while somebody is on the escalator). In the last two cases there has to be an alternative nearby.

Escalators in the London Underground used to have wooden steps, but this was changed after the King's Cross fire at King's Cross station in 1987. Escalators now have metal steps in a continuous loop that move on tracks. Escalators are typically used in pairs with one set going up and another going down.